Tension control for the let-off mechanisms of looms



Dec. 8, 1953 G. w. KRETZSCHMAR TENSION CONTROL FOR THE LET-OFF MECHANISMS OF LOOMS Filed Aug. 26, 1950 2 Sheets-Sheet l s R Y A E mm N m M s EZ W WU A IR & K w m o Y B a 1953 e. w. KRETZSCHMAR 2,661,773

TENSION CONTROL FOR THE LET-OFF MECHANiSMS OF LOOMS Filed Aug. 26, 1950 '2 Sheets-Sheet 2 Q 0 x) i INVENTOR. is) q 6:020: W. Manse/ MAR OLM Patented Dec. 8, 1953 UNITED I TENSION CONTROL FOR THE LET-OFF MECHANISMS OF LOOMS George W. Kretzschmar, Ridgewood, N. J. Application August 26, 1950, Serial No. 181,663

3 Claims. I

This invention relates to a visible and balanced tension control device for the let-01f mechanisms of looms and the like, especially let-off mechanisms of the positive type.

During weaving operations, the warp is subjected to a longitudinal stress or tension by the take-up mechanism which acts progressively to take up the cloth as it is woven and such tension is subjected to a variation by the shed formation and beat-up of the reed. As the weaving proceeds, the diameter of the warp on the beam gradually diminishes and the rotative movement of the beam is increased as the warp becomes smaller in diameter. However, the tension is held constant or uniform for any diameter of warp and throughout the run thereof by a tension roller mounted in a tension unit between the whip roller and the warp beam because the resultant formed by the parallelogram of forces remains constant. The active or operating tension has long been determined from experience and varies with the type of warp and cloth construction.

When the loom is at rest, the warp and cloth either stretch or shrink due to varying atmospheric conditions as well as the construction of the weave. With the warp stretches while the loom is at rest, the tension on the threads decreases, and when the warp has shrunk the tension increases so that the tension becomes less or greater than theactive or operating tension. When a loom is started from a position at rest and the Warp has stretched, usually a light mark appears in the weave. When the warp has shrunk on a loom at rest and the loom is started, usually a dark mark appears in the weave. The light and dark marks are called starting marks.

The beat-up or the impact of the reed is obtained through momentum, that is the impetus due to the motion of the lay stroke and is rela tively weak on the starting stroke or first pick. In practice, the weaver is instructed to manually open the lay structure fully on a loom at rest before standing the loom. However, this is seldom done with the result that the first beat up or the reed is weaker than when the loom is in operation. Spring or tight reeds also produce light or heavy impacts. All of which are factors varying the force of the impact of the first pick.

It is an object of the instant invention to provide a visible gauge reading of the warp and cloth tension at all times, whether the loom is in motion or at rest.

A further object is to provide looms with compensating means by which the tension on a machine at rest can be readily increased or decreased and returned to the operating tension before the loom is started.

Another object is to provide means by which tension can readily be increased over or decreased under operating or active tension to compensate for weaker impact or beat-up of the reed against the weave when the cloth and warp have stretched or to compensate for stronger impact of reed against reed when the cloth and warp have shrunk When the loom is at rest or after a pick-out of filling threads on a loom at rest.

Still another object is to provide at all times a balanced or equalized tension, that is equal pressure on both sides of the tension unit.

It is also an object of the instant invention to provide means for eliminating and preventing starting and joining marks, shirrs, barre, and all unevenness of weave.

An additional object is to provide a means on any loom for uniformity of weave.

Other objects of the instant-invention will become apparent in the course of the following specification.

In the attainment of these objectives, a visible and balanced tension control device is provided. The device is constituted of an auxiliary cylinder or tube mounted on each side of the loom below and upwardly directed toward the free end of the pivotally mounted tension unit. On each auxiliary cylinder or tube is a plunger or piston and in operable engagement with each piston and the tension unit of the loom is a compression spring. A hollow master cylinder is interconnected with the auxiliary cylinders and in the cylinders so connected is a fluid. Mechanism is provided in the master cylinder for forcing the fluid into the auxiliary cylinders and to permit it to return to the master cylinder in order to vary the compression of the springs against the tension unit and in turn the tension in the warp threads passing overthe rollers of the tension unit. A gauge connected with the fluid system gives a visible indication at alltimes of the magnitude of the tension of the warp threads and the weave while the tension control device provides a means for varying the tension.

The invention will appear more clearly when taken in conjunction with the accompanying drawing showing by way of example a preferred embodiment of the inventive idea.

In the drawing:

Figure 1 is a schematic longitudinal sectional View of the visible and balanced tension control device constructed in accordance with the principles of this invention;

Figure 2 is a plan view of the control device shown in Figure 1; and Figure 3 is a schematic diagram of the parallelogram of forces showing the action of the tension unit.

Referring now in greater detail to the drawings where like reference numerals. indicate like parts, reference numeral Ill indicates the tension unit, II the warp beam, It the take-up roller, and 13 the visible and balanced tension control device.

The tension unit is constituted of they whip. roller I4 and the tension roller l5 rotatably mounted by any known means between the end; member 16 and a similar end member on the. op.-. posite side of the loom, the end members being pivotally mounted on the shaft lGa of the ten,- sion roller. The shaft [6a, in turn, is rotatably supported-orroppositesides of the loom frame-in aeknown manner, All pivotsandgud ons. are mounted on ball bearings to obtain: quick acting motion onalk movable parts, When the warp travels over. a tension, rollerand a. whip. roller to the; take-up roller, ,theangle PAP, Fig, 3, formed-.by the; whip. roller; with the take up and tension, rollers; for any diameterof warp beam remains constant. Thus, the resultant of the arallelogram ofifprces hown n i ur 3'1emeins constant; AR and. r pr sent the to of the:v tension. on. the; warp. and AR the resultant.

The visible and balanced tension control device [34 is; constituted of a. shelf; I] attached as desiredto the warp. stand-or loom frame; on oppositeqsides; and adjacent.thew rpbeam H.

Threaded. throughthe bottomof each shelf ll isa tubular mcmbenor tube or. ili y ylin 1'8. with open ends; one end: pro r din b low the bottom and the other endextendingupwardlyor upwardly? and; forwardly; in thedirection of the whip roller IA; Reciprocable on; tube or tubular-member .l8.-is-, a plunger or piston 19, the upwardly directed.end;of .which. is; closed as-illustrated and substantially directed toward the shaftof the-whip roller Mar-thenceend of the end member. Adjacent the bottom of ach Di tonisanintegrally formed.1and-ZQ-. A Spring; isplaced around the-outer; surface. oi each piston between, the landrfll-and, a. downwardly directed arm 21c pivotally: mounted. on; the. end member of the; tension. unit. adjacent the; whip rolleig. Any; suitable protuberance; atthebaseof the arm 21 maybe used to retaimthe. prin m m r: in position. or. course, theuforce of; e springs could. be directed againstthe shaft of thewhip roller orv even, against thewh n roller. to; ac,- co'mplishi; the, same. end.v

At the opposite end-oi the loom orgin any other suitable location is a. masterhcylinder 252 which,

may be formedv with the'hollow and internally threaded: cylindrical member 2.6;with; open: ends, the bottombeing closed by; a base. member 2 1 threaded over theopen. bottom The .open top ofthe. cylindrical member 26 is internally threaded for; the insertion of an, externally threaded cylindrical head, 28, actuated by. any suitablerhandle member: 2.9.,

The tube, or.- tubularmember- I18;. and. the. cy-

lindrical member 2610f; the master-cylinder v are.

connected. byv a tubev or pipe; line- 30, the tube to the auxiliary cylinder on the. oppositeside. of the loom bifurcating from the tube 30'-.at the point A. pressure fiuidin themasten and a ilia cylinders and connecting tubes or pipe lines provides a means for varying the compression of the spring 2! of each auxiliary cylinder and in turn the force of the tension unit l0 against the warp threads.

In operation:

Suppose that the pressure gauge 32 connected into the tube of the visible and balanced ten sion control device I3; under: normal running conditions of theloom gives a reading of M pounds, and that the loom is closed down for a period of time. Variations in atmospheric con ditions. duringthe. shutdown period may cause the Warp; threads to stretch to such an extent that when it is again desired to start the loom iii-is found thatthe reading on the gauge has fallento N. pounds. By threading the cylindrical head 28 of the master cylinder 25 into the cylinder 26 with the handle member 29, the liquid in the master cylinder will be forced out and throughthe tube or pipe 1ine3 0. toeach auxiliary cylinder. Passin thro h. thev tubular mem: ber l8 of each. auxiliary cylinder, the fluid. will be forced into. the. pocket 33 between the tubular member; and the piston until. sufficient pressure has been built up to move, the piston l9 outwardly toward the. tension. unit and with it the land. 20 which cQmpressesthQ spring 2! againstthe pivotally. mounted. arm 21141 on eachend of the tension, unit. The, increased compression of the. springs. 21 in. turn forces the tension unit. to to rotate. clockwise about. the pivotal point Ifiaand againstlthe warp. threads until thetension thereon. is thesame. as. that .used in the normal operation or 'M pounds. 011,-, the other hand, if thewarpthreads shrink during, the shut-down period and. the tension on. thewarp threads has increased, thev reverse of the previously described steps willlrestore the, desired operating tension on the warpthreads. During the normal runningconditions, a. glanceat the gauge will quickly show any deviation ofthe ten.- sion from normal and the control device-will, pro.- vide a simple, ready, and. inexpensive, means. for correcting the variation. now. chiefly guesswork and concerning which .few persons ever agree. By using.- the; two tension, control units, one, on each end of the tension, unit, variations in. tension on: the; warp threadscausedby uneyenwarping and eccentricity of.warp is.likewise, under control for the tension oi the; springs. against thetension unitis thesame onboth sides of that unitirrespectiyeof the. inclination of thetension on unit. relative to thehorizontal. Ona. loom at rest or in motion. the .tensionon the warp and cloth can readily bemade greateror less. than the operating, or active tension thus compensating for variations in, impact. or beat-.up of the reed. against the. weave. Withthe tension. unit Ill-providing a constant. tensionhon the warp threads irrespective ot the diameter of. thewarp beam H, thevariations. in tension arising from the stretching. and shrinking of thewarp, threads the wear ofmthe. machine and. the. variations of beat-up of the. reed-under. controL. it is possibli to. produce av cloth substantially free from defects and to eliminate: Waste.

Whilethe mechanism described for. varyingthe tension on thewarp. threads hasbeenhydrauli'c, the same, desirable resultscould be attained. by using electrical-,,'mechanical, electroemechanical, or pneumatic means, Hence, it will beunderstood that the invention is. notlimitedto the exact. disclosure herein, described but m y lend itself t avariety of. expressions w h n h sc pe of the appended claims.

What is claimed is:

1. In a loom having a frame of spaced side members, a warp beam rotatably mounted in one end of the frame, and a tension unit one end of which is pivotally mounted between the side members and above the warp beam; the improvements comprising a tension control device for the tension unit, the tension control device comprising an auxiliary cylinder disposed on each side member of the loom below the tension unit, the top of each auxiliary cylinder being open and upwardly directed toward the free end of the tension unit, a piston reciprocable on the outside of each auxiliary cylinder, the top of each piston being closed and in opposed relationship with the open top of the auxiliary cylinder, a spring member in operable engagement with each piston and the corresponding free end of the tension unit, means for simultaneously introducing a fluid pressure into each auxiliary cylinder and piston, and means for simultaneously releasing the fluid pressure from each auxiliary cylinder and piston.

2. A tension control device in combination with the tension unit of a loom, the 100m having side members and the tension unit having a whip roller and a tension roller rotatably mounted between end members with the end members pivotally mounted about the tension roller journaled in the side members of the loom; the tension control device comprising an auxiliary cylinder disposed on each side member of the loom, the top of each auxiliary cylinder being open and upwardly directed toward the whip roller, a piston reciprocal on the outside of each auxiliary cylinder, the top of each piston being closed and in opposed relationship with the open top of the auxiliary cylinder, a spring member in operable engagement with each piston and the corresponding end member adjacent the whip roller, a pipe line interconnecting each auxiliary cylinder, a master cylinder coacting with the auxiliary cylinders, a second pipe line interconnecting the master cylinder with the first mentioned pipe line, a pressure fluid for the cylinders and interconnecting pipe lines, and means for varying the volume of the pressure fluid in the master cylinder.

3. A tension control device for the tension unit of a loom, the tension unit having a whip roller and a tension roller rotatably mounted between end members at the top of the loom adjacent the warp beam, and the end members being pivotally disposed about the tension roller with the whip roller inwardly directed therefrom; the tension control device comprising an auxiliary cylinder for each side of the loom, means for securing one end of each auxiliary cylinder to the side of the loom below the tension unit, the top of each auxiliary cylinder being open and upwardly directed toward the whip roller of the tension unit, a piston reciprocable on the outside of each cylinder, the top of each piston being closed and in opposed relationship with the open top of the auxiliary cylinder, each piston having an integrally formed land, a spring disposed intermediate the land and the corresponding end member adjacent the whip roller, a pipe line interconnecting the auxiliary cylinders in parallel, a master cylinder coacting with the auxiliary cylinder disposed on the loom, a second pipe line interconnecting the master cylinder with the first mentioned pipe line, a pressure fluid disposed in the cylinders and pipe lines, means for varying the fluid pressure comprising an open top on said master cylinder and an internally threaded open-' ing formed in the open top, an externally threaded cylindrical head coacting with the internally threaded opening in the master cylinder, and a pressure fluid gauge disposed in one of the pipe lines.

GEORGE W. KRETZSCHMAR.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 2,164,596 Simonds July 4, 1939 2,296,753 Wilton Sept. 22, 1942 2,507,828 Stephansen et a1. May 16, 1950 2,539,295 Clentimack Jan. 23, 1951 FOREIGN PATENTS Number Country Date 525,839 Great Britain Sept. 5, 1940 

